The northern province of Tak on Saturday sealed its border shared with Myanmar's Myawaddy after three more Myanmar nationals in Mae Sot border district tested positive for the new coronavirus that causes Covid-19.
That prompted the Myanmar town to close its immigration checkpoint on the opposite side of Mae Sot's immigration checkpoint as well, a source said.
The border shutdown was one of a number of stricter Covid-19 prevention measures imposed on the border district after the three were found to have the virus in an initial round of Covid-19 tests, Tak governor Phongrat Phiromrat said.
They are a daughter, a niece and nephew of a Myanmar couple who tested positive for the virus earlier last week, he said.
Results of a repeat Covid-19 test on the three cases still are pending, said the Department of Disease Control.
The department's chief, Opas Karnkawinpong, said results of the repeat test are required before the infections can be confirmed. Positive results of their first Covid-19 tests were known on Friday, he said.
The 53-year-old Myanmar woman and her husband, 63, who lived in Mae Sot district, tested positive on Tuesday, but showed no symptoms, according to the Centre for Covid-19 Situation Administration (CCSA). The five asymptomatic Covid-19 patients are receiving treatment at Mae Sot Hospital, Dr Opas said.
The infected daughter, niece and nephew are among five people who are either family members of the infected couple or relatives who were in close contact with them before they tested positive, Mr Phongrat said.
Four other people treated also as the couple's close contacts are Myanmar migrants visiting a mosque called Madina, Dr Opas said, adding the nine were being quarantined by the time the three tested positive for the virus.
Local authorities have since put two communities, Thung Thong and Madina Mosque, linked with these five new Covid-19 cases under strict disease control, the governor said.
The couple was found to have the virus in screening Covid-19 tests carried out previously in several communities of Mae Sot after two drivers and one Myanmar worker at one warehouse tested positive on Oct 9 and 10 respectively, he said.
It is believed the two were infected by either their son who had returned from Rangoon or relatives who are border vendors, according to another source.
The department's fast-deployment teams are still screening residents in areas linked with the infected couple's activities, including some markets and the mosque, Dr Opas said.
About 55 people in this low-risk group were told to closely motor their health instead of being required to undergo Covid-19 quarantine, Dr Opas said.
More Covid-19 tests had already been conducted among 61 people attending a religious ceremony at the mosque, none of which was infected, he said.
In another development, 39 Thais released from detention in Malaysia have been sent home through Sadao border checkpoint. They went through Covid-19 examinations and entered 14-day local quarantine venues near the border.